Validation and Improvement of a Highly Predictive Bariatric Surgery Mortality Risk Calculator to Include Sleeve Gastrectomy Using MBSAQIP 2015-2017 Data

Background: Initial development of a prominent bariatric surgery mortality risk calculator comprising cases that now account for <10% of commonly performed operations. Whether the previously highly predictive model is valid with more recent data is unknown. Objectives: To validate and improve a bariatric-surgery-specific mortality calculator with updated case mix and outcomes data. Setting: Metabolic and Bariatric Surgery Accreditation and Quality Improvement Program-accredited bariatric surgery programs. Methods: The Metabolic and Bariatric Accreditation and Quality Improvement Program Participant Use File from years 2015 to 2017 was used for the analysis. C-statistics were calculated with observed death as the outcome and estimated 30-day mortality risk as the only predictor and receiver operating characteristic curve was plotted. Similar analyses were repeated for each body mass index (BMI) subgroup. Backward selection logistic regression was used to investigate the potential of improving the robustness of the model. Results: Patients were predominantly female (n = 446,149, 80.4%) and white (n = 409,350, 73.7%) with a mean (standard deviation) age of 45.4 (12.0) years and BMI of 44.5 (8.4) kg/m(2), and the most commonly performed operation was sleeve gastrectomy (n = 338,061, 60.9%). Assessing previous model using present data, area under the curve was .7412. By BMI subgroup, area under the curve for BMI <45 kg/m(2) was .7645, for BMI 45 to 60 kg/m(2) was .7586, and for BMI >60 kg/m(2) was .6576. Discussion: The present study found that the model previously developed maintains discrimination with changing surgical procedures. Though variables in the initial calculator are helpful, additional factors should be considered when weighing risk, such as sex, previous surgery, and renal function. Future studies are needed to determine whether changes in modifiable risk factors will impact mortality rates. (C) 2020 American Society for Bariatric Surgery. Published by Elsevier Inc. All rights reserved.